1. Field of the Invention
This invention relates to marine structures and in particular to structures such as boat stations and piers.
2. Description of the Prior Art
In conventional marine structures, such as boat stations and piers, adapted for installation at the shore of a body of water, such as a lake or river, a submerged portion of the structure is provided resting on the marine bottom and extending upwardly therefrom to above the surface of the water.
In the conventional boat station, the structure includes a hoist portion which is movable vertically between a boat receiving position and a boat raising position, such as for storing the boat out of the water. Handwheel or electric motor means may be provided for effecting the desired movement of the movable portion of the boat station suitably geared to permit a person to move the relatively heavy boat between the floating and storage positions.
Similarly, in conventional pier constructions, footings are placed in the water extending down to the bottom for supporting a deck above the upper surface of the water.
Conventionally, such boat stations and piers must be removed each winter to avoid damage thereto by ice movement on the surface of the body of water during the winter months.
A number of structures have been developed wherein the portion of the structure extending to above the water level may be stored below the water level when desired. More specifically, as shown in Russel B. Smith U.S. Pat. No. 3,216,704, a boat hoist is provided having a boat support portion which is pivotally retractable to below the normal water level, when desired. An upright is provided carrying a winch for controlling the retractable support portion. The winch mounting means is maintained extending to above the water level at all times and, thus, the Smith patent presents the problem discussed above of having one or more portions of the marine structure extending to the ice level whereby movement of the ice during the winter months may damage and move the marine structure. There is no teaching in the Smith patent of any specific disposition of the hoist in the retracted position relative to the exposed ice depth.
In U.S. Pat. No. 2,505,832 of Anthony C. Lange, a boat hoist is shown which is retractable to below the water line by means of a pump.
U.S. Pat. No. 3,753,355 of Glen C. Knoch, shows a boat hoist provided with a winch and cable means for pivoting an upper boat support portion on a lower frame. The winch portion is similar to that of Smith in extending to above the water level at all times.
Byron L. Godbersen, in U.S. Pat. No. 3,169,644, teaches the provision of means for mounting automobile tire wheels on the boat hoist permitting it to be moved more readily into and from the water so that the structure may not only serve as a boat hoist, but as a trailer.
Other prior art patents showing generally the use of similar boat handling apparatus are those of Hiram L. Sarver U.S. Pat. No. (1,369,194), David M. Murphy U.S. Pat. No. (2,934,220), Edward E. Harvey U.S. Pat. No. (3,021,965), and Harry W. Schollard U.S. Pat. No. (3,220,196).
Sarver U.S. Pat. No. 1,369,194 shows an automobile lift but does not even remotely suggest a marine installation similar to applicant's installation. Murphy U.S. Pat. No. 2,934,220 shows a boat lifting device which is similar to the Knoch patent in providing a structure having at least one portion which would extend to above the water level at all times. Edward E. Harvey U.S. Pat. No. 3,021,965 shows a retractable boat lift without any teaching of the relationship thereof to the freeze zone in a marine installation, and Schollard U.S. Pat. No. 3,220,196, shows a boat dock without any relationship to the freeze zone of a marine body of water.